JPH0426750Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a hydraulic shock absorber, and in particular, when the vibration frequency of the oil chamber in the cylinder exceeds a set range,
The present invention relates to an improvement in a hydraulic shock absorber that enables a so-called high-cut action in which the previously high damping force is reduced.

[Conventional technology]

Various types of hydraulic shock absorbers have been proposed in the past that enable a so-called high-cut action in which the damping force is reduced when the vibration frequency of the oil chamber in the cylinder exceeds a set range. However, the applicant of the present application also proposed a hydraulic shock absorber having a structure as shown in FIG.

That is, the piston part 2 housed in the cylinder 1
In a piston nut 21 for fixing the piston main body 20 to the lower end of the piston rod 3, there is disposed a damping force generating section 4 that is capable of generating a damping force on the rebound side and also reducing the damping force. It is assumed that the

The damping force generating section 4 includes a leaf valve 40 that can generate a predetermined amount of damping force by bending its outer peripheral end, and a support member 41 that supports the leaf valve 40 from the bottom side. a push member 42 that comes into contact with the upper surface of the inner circumferential side of the leaf valve 40, and the push member 42 is lowered from above by a pressing force to lower the inner circumferential end of the leaf valve 40. When the leaf valve 4
It is formed so that the damping force on the expansion side that is generated when the hydraulic oil passes by bending the outer peripheral end of the cylinder 0 is increased.

Furthermore, in the damping force generating section 4,
A pressure chamber R is formed above the push member 42, and the pressure chamber R is connected to the piston rod 3.
It communicates with the rod-side oil chamber A through an orifice O through an inner passage 3a so as to become a pressure chamber with a first-order lag with respect to the oil chamber in the cylinder 1, that is, the rod-side oil chamber A.

Note that the hydraulic oil from the passage 3a flows into the upper surface of the outer peripheral side of the leaf valve 40 through a port 43a of a block member 43 that accommodates the push member 42.

Therefore, in the conventional example proposed by the applicant mentioned above, it is possible to enable a so-called high-cut action depending on the vibration frequency in any oil chamber in the cylinder by setting the orifice O. .

[Problem that the invention attempts to solve]

However, in the above-mentioned conventional proposal, the orifice O forming the first-order lag pressure chamber R is fixed, so that a so-called high cut effect is caused based on the set vibration frequency range. There is a disadvantage that the point at which the damping force changes, that is, the timing at which the high-cut action occurs cannot be made variable.

That is, in the above-mentioned conventional proposal, the usage conditions of the hydraulic shock absorber tend to be fixed, and its versatility cannot be obtained.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a new hydraulic shock absorber that can have a wide range of vibration frequencies that produce a so-called high-cut action, thereby increasing its versatility.

[Means for solving problems]

In order to solve the above-mentioned problems, the structure of the present invention is formed so that the deflection characteristics of the leaf valve can be changed by the internal pressure in the first-order lag pressure chamber that communicates with the cylinder internal oil chamber through an orifice. In a hydraulic shock absorber, an orifice is formed by a plate member having an oil hole that partitions the pressure chamber and a lower end of a rod body that moves by operation of an actuator, and the rod body is connected to the plate member. This is characterized in that the opening area of the orifice can be adjusted by moving the orifices closer together.

[Effect]

When the lower end of the rod body approaches the plate member, the orifice formed between the lower end of the rod body and the plate member causes the vibration frequency in the pressure chamber of the first order lag to reach the vibration frequency in the oil chamber in the cylinder set by the orifice. It is possible to prevent the generation of internal pressure, and it is possible to arbitrarily stop the generation of high damping force by changing the deflection characteristics of the leaf valve.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

As shown in FIG. 1, a hydraulic shock absorber according to an embodiment of the present invention has a piston part 2 in a cylinder 1, and has the piston part 2 at the lower end and the upper end of the cylinder 1. It has a piston rod 3 which projects outward in the axial direction. The inside of the cylinder 1 is connected to the rod side oil chamber A by the piston part 2.
It is divided into a piston side oil chamber B and a piston side oil chamber B.
The oil chambers A and B on both sides are formed so as to be able to communicate with each other through the piston portion 2.

An outer tube 10 is disposed outside the cylinder 1, and the outer tube 1
0 and the cylinder 1 is a reservoir chamber C, and above the reservoir chamber C is a gas chamber D. A so-called base valve section 12 is formed in a bottom member 11 disposed so as to close the lower ends of the cylinder 1 and the outer tube 10.
The piston-side oil chamber B and the reservoir chamber C can communicate with each other through the piston-side oil chamber B.

The base valve portion 12 is provided with a throttle 12a as a pressure damping valve, a check valve 12b for blocking pressure side flow, and a relief valve 12c for setting the pressure side damping force. Further, a bearing member 13 is disposed at the upper end of the cylinder 1,
A seal member 14 is housed inside the upper end of the outer tube 10.

The piston portion 2 has a compression side port 20a on the outer circumferential side of the thick portion of the piston body 20, and has an expansion side port 20b on the inner circumferential side thereof. and,
The lower end of the pressure side port 20a is the piston side oil chamber B
The upper end is opened to the rod side oil chamber A. The lower end opening of the expansion side port 20b is connected to a piston nut 21 screwed onto the lower end of the piston rod 3 in order to fix the piston main body 20 to the lower end of the piston rod 3.
The upper end of the port 21a is opposed to the upper end of the port 21a. Note that a check valve 2 is provided at the upper end opening of the pressure side port 20a.
2 are facing each other.

The piston nut 21 has an inner chamber 21b in which the lower end of the port 21a opens. A damping force generating section 4 is provided within the inner chamber 21b.
have.

The damping force generating section 4 includes an annular leaf valve 40 that can generate a predetermined amount of rebound damping force by bending its outer peripheral end. piston nut 21
The leaf valve 40 is engaged with a support point 41a on the upper surface of a support member 41 screwed inside the lower end thereof, and a pressing point 42a of a pusher member 42 is brought into contact with the upper surface of the inner peripheral end of the leaf valve 40. The outer peripheral end is a free end so as to be able to bend downward, and is formed so that when hydraulic oil flows into the upper surface of the outer peripheral side, the outer peripheral end bends downward and generates a predetermined damping force. There is.

The push member 42 is connected to the leaf valve 4.
The coil spring 44 is housed in the center of a lock member 43 located above 0 so as to be slidable, that is, vertically movable, and the lower end of a coil spring 44 is in contact with the upper surface of the lock member 43. A spool 45 is disposed at the upper end of the coil spring 44, and the spool 44 defines a pressure chamber R inside the center of the block member 43.

In this embodiment, a plate member 46 is disposed on the upper end surface of the block member 43, and the plate member 46 defines the pressure chamber R together with the block member 43 and the spool 45. It is said that Further, an oil passage hole 100 is bored in the center of the plate member 46, and the pressure chamber R is an oil chamber in the cylinder.
That is, it is in communication with the rod side oil chamber A through the oil passage hole 100.

A through hole 46a is provided on the inner peripheral side of the plate member 46.
A check valve 47 is adjacent to the upper surface of the plate member 46 so as to close the through hole 46a from above. The check valve 47 is urged downward by a spring 50 whose upper end is engaged with a stopper 49 disposed within a spacer member 48 disposed above the plate member 46. There is.

Note that the check valve 47, stopper 49, and spacer member 48 are each provided with a central portion in the center so that the hydraulic oil in the inner chamber 21b of the piston nut 21 can flow into the front side of the oil passage hole 100 without resistance. Large through holes 47a, 49a, and 48a are formed. Further, a plate member 4 is provided on the outer peripheral side of the plate member 46 and the spacer member 48.
A through hole 46b and a port 48b are formed in series with the port 43a bored on the outer peripheral side of the lower block member 43. Furthermore, a port 4 is provided on the outer peripheral side of the support member 41 below the leaf valve 40 to allow hydraulic oil to flow into the piston side oil chamber B through the outer peripheral end of the leaf valve 40.
1b is formed.

The lower end of a rod body 51 whose upper end side is housed in the piston rod 3 is inserted into the central through holes 48a and 49a of the spacer 48 and stopper 49, and the lower end of the rod body 51 is
Orifices O are formed between the plate members 46 at appropriate intervals.

A flange portion 51 is provided at the upper end of the rod body 51.
A is formed, and the upper end of a coil spring 52 housed in the axial hole 3a of the piston rod 3 is in contact with the lower surface of the flange portion 51a.
is energized so that it can slide upward.
It goes without saying that the rod body 51 overcomes the urging force of the coil spring 52 and descends within the piston rod 3.

The lower end of an actuator 53 made of a piezoelectric element is in contact with the upper end of the rod body 51. A spacer 54 is provided at the upper end of the piezoelectric element body, and the spacer 54
An adjustment rod 55 is screwed inside the upper end of the piston rod 3 so as to fix the upper end of the piezoelectric element body through the adjustment rod 55.

Then, the spacer 54 and the adjustment rod 5
Through holes 54a and 55 formed in each axis of 5
A lead wire 53a connected to the piezoelectric element body serving as the actuator 53 is inserted through the inside a, and the end of the lead wire 53a is extended to the outside of the piston rod 3.

By screwing together the adjustment rod 55, the entire actuator 53, which is a piezoelectric element body, can be lowered or raised via the spacer 54, that is, the actuator 53 can be lowered or raised as a whole through the spacer 54.
The lower end of the rod body 51 that comes into contact with the lower end can be selected to be raised or lowered.

Further, the actuator 53 changes its axial length by applying a voltage from the outside, but in particular, since the upper end is fixed, the displacement in the extension direction is changed through the rod body 51. hand,
It will be exposed at the lower end of the rod body 51.

That is, the lower end of the rod body 51 is connected to the plate member 46.
approach the lower end surface of the rod body 51 and the oil passage hole 100.
The opening degree of the orifice O formed between the plate member 46 and the upper surface of the plate member 46 having the rod side chamber A is changed.
This restricts the propagation of pressure from the pressure chamber R to the pressure chamber R.

As a result, the pressure chamber R, which communicates with the cylinder oil chamber, that is, the rod side oil chamber A, through the oil passage hole 100 is allowed to receive hydraulic oil at a flow rate smaller than that of the oil passage hole 100. Therefore, the vibration frequency in the cylinder oil chamber is lower than that of the oil passage hole 100.
Internal pressure is no longer generated within the pressure chamber R in a lower vibration frequency range than in the case of .

In a so-called low vibration frequency region where a first-order lag internal pressure is generated in the pressure chamber R, pressure propagation is relatively smooth, so that the lowering of the spool member 45 causes the pressure to propagate through the coil spring 44. However, the push member 42 descends within the block member 43 and pushes down the inner peripheral end of the leaf valve 40, and the outer peripheral end of the leaf valve 40 is pushed upward by the so-called lever principle.

As a result, when the piston part 2 moves upward in the cylinder 1 on the expansion side, the expansion side port 20b of the piston body 20 and the port 21a of the piston nut 21
When the hydraulic oil flowing into the upper surface of the outer circumferential side of the leaf valve 40 bends the outer circumferential end of the leaf valve 40 and flows out into the piston-side oil chamber B, a high damping force is generated. Then, when high internal pressure is no longer generated in the pressure chamber R, the pushing force that pushes down the inner peripheral end of the leaf valve 40 is removed from the pusher member, and the leaf valve 40
The outer peripheral end deflection characteristic of 0 is returned to the initial setting, and the damping force is adjusted to be low.

The generation of high internal pressure in the pressure chamber R can be prevented even in a lower vibration frequency range by further restricting the amount of oil passing through the orifice O. It is sufficient if the orifice O formed between the upper surface of the plate member 46 and the upper surface of the plate member 46 is made smaller.

[Effect of idea]

As described above, according to the present invention, what is considered to be a high damping force up to an arbitrarily set vibration frequency range becomes a low damping force when the vibration frequency exceeds the above range. There is an advantage that not only the operation is possible but also that the above-mentioned transformation area can be made variable.

In addition, since the selection of the conversion region is made possible by applying voltage to the piezoelectric element body serving as the actuator, it can be done with an extremely simple operation, and
Since the actuator is installed within the main body of the hydraulic shock absorber, there is also the advantage that there are fewer restrictions on installation when installing the hydraulic shock absorber in a vehicle or the like.

Furthermore, according to the present invention, since the actuator is housed within the hydraulic shock absorber body, there is also the advantage that there is no risk of external failure of the actuator due to exposure to muddy water after installation in a vehicle, etc. .

As a result, according to the present invention, the range of use of the hydraulic shock absorber is less likely to be limited by vehicle type or usage conditions, and its versatility is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a hydraulic shock absorber according to an optimal embodiment of the present invention, and FIG. 2 is a partially cutaway front view showing a hydraulic shock absorber according to a conventional example. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston part, 3... Piston rod, 4... Damping force generating part, 20... Piston body, 21... Piston nut, 40...
Leaf valve, 46...Plate member, 51...
Rod body, 53... Actuator, A... Rod side oil chamber, B... Piston side oil chamber, C... Reservoir chamber, D... Gas chamber, O... Orifice, R...
pressure chamber.

Claims (1)

[Claims for Utility Model Registration] (1) Hydraulic buffer formed so that the deflection characteristics of the leaf valve can be changed by the internal pressure in the first-order lag pressure chamber that communicates with the cylinder oil chamber via an orifice. In the device, the orifice is formed by a plate member provided with an oil hole that partitions the pressure chamber and a lower end of a rod body that moves when the actuator is operated, and the rod body is brought close to the plate member. A hydraulic shock absorber characterized in that the opening area of the orifice is adjustable. (2) The hydraulic shock absorber according to claim 1, wherein the actuator is made of a piezoelectric element and is housed in a piston rod. (3) The hydraulic shock absorber according to claim 1, wherein the rod body is housed within the piston rod. (4) Utility model registration claim 1, in which the pressure chamber is formed in a piston nut that fixes the piston body of the piston portion to the lower end of the piston rod.
Hydraulic shock absorber as described in section. (5) The hydraulic shock absorber according to claim 1, wherein the leaf valve is housed in a piston nut that fixes the piston body of the piston portion to the lower end of the piston rod.